The impact of Blastobasis repartella (Dietz) (Lepidoptera: Coleophoridae) on switchgrass

The impact of Blastobasis repartella (Dietz) (Lepidoptera: Coleophoridae) on switchgrass Veronica Calles Torrez, Insect Biodiversity Laboratory, Department of Plant Science, South Dakota State University – Brookings, SD; Dr. Paul J. Johnson, Insect Biodiversity Laboratory, Department of Plant Science, South Dakota State University – Brookings, SD; Dr. Arvid Boe, Department of Plant Science, South Dakota State University – Brookings, SD Switchgrass (Panicum virgatum L.) is a potential biomass production crop and is important as a model organism for native species-based biofuel synthesis. A potential pest, the Switchgrass moth (Blastobasis repartella (Dietz)) larva feeds in the rhizome, proaxis, and basal internodes of the tillers, causing premature death of buds and tillers that directly affect biomass accumulation. The focus of this study was to determine among cultivars the frequency of tiller infestation, and the differences in biomass production and biomass loss. Sampling in 2011 of tillers was conducted in older (planted 2004) and newer plots (planted 2008) at Brookings, South Dakota. Both plots were arranged in a Randomized Complete Block design with six replications of six cultivars. A 0.30 m2 frame was used to delimit sample areas and all tillers within were cut at ground level. Tillers were categorized as infested and uninfested, counted, dried at room temperature, and weighed. Analysis of variance for differences was used with the least significant difference to compare means. Differences among cultivars were seen in biomass yield and in biomass loss in the 2008 plants due to tiller infestation but not in the 2004 plants. No differences were found among cultivars in frequency of infestation at either plot. Blastobasis repartella affected the biomass production by cultivar and plant age during the early seasonal growth stages. Further, subterranean damage evaluation is needed to fully understand the complete impact of B. repartella on potential switchgrass biomass production due to the loss of overwintering tiller and rhizome buds.